If you play a directory with shuffle on, the playlist position tag
(%pp) displays really the position of the track within the playlist
(not the directory), *but* :

- if 'play selected first' is on, the playlist starts with the
selected track, which has a random position. %pp displays for
instance 5, 6, 7, 8, 1, 2, 3, 4.
I've submitted a patch to display the rigth position (from 1 to N) in
WPS and ID3.
(Display right position of track in shuffled directory: 700465)

- if 'play selected first' is off, but you select the 4th track in
directory (for instance), then the first track played is the 4th in
the shuffled playlist. %pp displays 4, 5, 6, 7, 8. (if repeat is
'all', it's not so visible.)
If this is not a wanted feature, I've submitted a simple patch to
play the entire shuffled directory when 'play selected first' is off.
(Play all tracks in shuffled directory: 700467)